Hypertension In Pregnancy

Hypertension in Pregnancy N.L. Meyer, M.D.

Hypertension in Pregnancy • Most common medical disorder during pregnancy • Gestational hypertension – preeclampsia • 70 % of HTN in pregnancy • Wide spectrum • Mild elevation in BP vs severe hypertension with organ dysfunctions • Acute gestational hypertension • Preeclampsia • Eclampsia • HELLP

Hypertension in Pregnancy Chronic Hypertension

Gestational Hypertension

< 20 weeks

Third trimester

≥ 20 weeks

Mild or severe

Mild

Mild or severe

Absent

Absent

Usually present

Uric acid > 5.5 mg/dl

Rare

Absent

Usually present

Hemoconcentration

Absent

Absent

Severe disease

Thrombocytopenia

Absent

Absent

Severe disease

Hepatic dysfunction

Absent

Absent

Severe disease

Clinical Findings Onset Degree Proteinuria

Preeclampsia

Gestational Hypertension • Systolic BP ≥ 140 and /or diastolic ≥ 90 on at least 2 occasions at least 6 hours apart after 20 weeks in women known to be normotensive before pregnancy and before 20 weeks gestation • BP recordings should be no more than 7 days apart • Severe gestational hypertension • Sustained elevations in systolic BP ≥ 160 and /or diastolic BP ≥ 110 for 6 hours

Gestational Hypertension • Most frequent cause of HTN during pregnancy • 6 -17% in healthy nulliparous patients • 2 - 4% in multiparous patients • Rates increase • Previous preeclampsia • Multifetal gestations

Gestational Hypertension • Progression • Gestational age at diagnosis • 50% progression with diagnosis prior to 30 weeks • Severe hypertension • Preeclampsia • Eclampsia • Undiagnosed hypertension

Gestational Hypertension • Most cases develop ≥ 37 weeks • Overall outcome similar to or better than normotensive pregnancies • Higher gestational age at delivery • Higher birth weight • Higher rates of induction • Higher cesarean section rates

Mild Gestational Hypertension Kuinst (n = 396)

Hauth (n = 715)

Barton (n = 405)

Sibai (n = 186)

Gestational age

NR

39.7

37.4

39.1

< 37 (%)

5.3

7.0

17.3

5.9

< 34 (%)

1.3

1.0

4.9

1.6

Birth weight (gm)

NR

3303

3038

3217

SGA (%)

1.5

6.9

13.8

7.0

< 2500 g (%)

7.1

7.7

23.5

NR

Abruption (%)

0.5

0.3

0.5

0.5

Perinatal death (%)

0.8

0.5

0

0

Mild Gestational Hypertension Management •Increased risks for progression •Close maternal and fetal assessment

Mild Gestational Hypertension Maternal Evaluation • Weekly prenatal visits • Reporting preeclamptic symptoms • Laboratory evaluation • CBC • Platelets • LFT's

Mild Gestational Hypertension Fetal Evaluation •Amniotic fluid •Estimated weight •Weekly nonstress testing

Mild Gestational Hypertension Management • Salt restriction – not indicated • Restricted activity – not indicated • Antihypertensive medication – not indicated • Continue to term • Absence of progression • Seizure prophylaxis – not indicated

Severe Gestational Hypertension • Increased maternal and perinatal morbidity • Outcomes similar to severe preeclampsia • Abruptio placentae • Preterm delivery • < 37 weeks • < 35 weeks • SGA infants • Manage as if they had severe preeclampsia

Severe Gestational HTN vs Severe Preeclampsia Outcome

Relative risk

95% CI

Delivery <37 wk

0.81

0.53-1.24

Delivery <35 wk

0.7

0.32-1.56

SGA infant

1.83

0.56-5.71

Abruption

0.63

0.07-5.69

LGA infant

1.87

0.28-12.49

NICU admissions

0.55

0.23-1.31

RDS

0.75

0.21-2.63

Buchbinder et al AJOG 2002;186:66-71

Preeclampsia • Hypertension unique to human pregnancy • Rarely reported in primates • Incidence • 3 - 7 % in nulliparas • 0.8 - 5 % in multiparas • Significantly increased in multigestations

Risk Factors • Nulliparity

• Preexisting medical conditions

• Family history

• CHTN

• Obesity

• Renal disease

• Multifetal gestation

• Diabetes

• Previous preeclampsia

• Thrombophilias

• Previous poor outcome

• APAS

• IUFD

• Protein S deficiency

• IUGR

• Protein C deficiency

• Abruption

• Factor V Leiden • Abnormal dopplers

Preeclampsia • Gestational hypertension plus proteinuria • ≥ 300 mg / 24 hours • Classic triad • Hypertension • Proteinuria • Edema

Hypertension • Systolic blood pressure of ≥ 140 mm or diastolic blood pressure of ≥ 90 mm after 20 weeks in a previously normotensive women • "30 x 15" rule • ↑ 30 mm SBP or 15 mm DBP over baseline • No longer used • Gradual rise in BP is seen in most normal pregnancies • 73% of primigravidas demonstrate >15 mm increase in DBP during pregnancy • 67% with SBP > 30 mm over baseline

Hypertension

Sensitivity

PPV

DPB ≥ 15 mm

39%

32%

SBP ≥ 30 mm

22%

33%

Villar and Sibai AJOG 1989;60:419

Hypertension • Korotkoff phase V • Appropriate size cuff • Length 1.5 x upper arm circumference • Bladder encircles > 80% of the arm • Upright position after ≥ 10 minutes rest • Hospitalized • Either sitting up or LLR position • Arm level with heart • No tobacco or caffeine x 30 minutes • Mercury sphygmomanometer preferred

Edema •No longer considered part of the diagnosis •Neither sufficient nor necessary to confirm •Common finding in normal pregnancies •1/3 of eclamptic women do not develop edema

Proteinuria • ≥ 300 mg / 24 hours • 30 mg/dL or ≥ 1+ on dipstick on at least 2 random samples at least 6 hours apart but < 7 days apart • Dipstick correlates poorly with protein in a 24-hr collection* • 1+ has PPV of 92% for ≥ 300 mg / 24-hr • Negative to trace has a NPV of only 34% • 66% have > 300 mg / 24-hrs • Cannot exclude significant proteinuria • 3+ to 4+ have PPV of 36% • Cannot confirm significant proteinuria * Meyer et al AJOG 1994;170:137-41

Proteinuria

Urine protein / 24hrs

Neg

Tr

1+

2+

3+

4+

< 300

21

21

9

3

3

0

300 - 4999

37

44

42

38

22

24

≥ 5000

0

0

2

7

10

17

Meyer et al AJOG 1994;170:137-41

Proteinuria

Dipstick mg / 24-hrs Sensitivity Specificity PPV

NPV

> 1+

≥ 300

67

74

92

34

> 3+

≥ 5000

75

81

36

96

Meyer et al AJOG 1994;170:137-41

Proteinuria • Can preeclampsia occur without proteinuria? • Consider preeclampsia when gestational hypertension is associated with other symptoms • Persistent cerebral symptoms • Epigastric or right upper quadrant pain with nausea and vomiting • Thrombocytopenia • Abnormal liver enzymes • IUGR

Severe Preeclampsia • Severe gestational hypertension associated with abnormal proteinuria • SBP ≥ 160 mm or DBP ≥ 110 mm on 2 occasions > 6 hours apart at bed rest • Hypertension in association with severe proteinuria • ≥ 5 g / 24 hours

Severe Preeclampsia • Multiorgan involvement • Pulmonary edema • Seizures • Oliguria • < 500 mL / 24 hours • Thrombocytopenia • < 100,000 / mm3 • Abnormal LFT with persistent RUQ or epigastric pain • Persistent severe CNS symptoms

Superimposed Preeclampsia • New onset proteinuria complicating hypertension prior to 20 weeks gestation • Sudden increase in proteinuria • Sudden increase in hypertension • HELLP syndrome • CHTN with HA, scotomata or epigastric pain

Management • Delivery is the only cure • Primary considerations • Safety of mother • Delivery of a live, mature newborn • Immediate delivery vs expectant management • Severity of disease process • Maternal / fetal status at initial evaluation • Gestational age • Labor • Bishop score • Maternal desire

Mild Preeclampsia - Management • Mild preeclampsia at term with favorable cervix • Delivery • Unfavorable cervix ≥ 37 weeks - ? Cervical ripening • Delivery ≥ 34 weeks • Progressive labor • ROM • Abnormal testing • IUGR • Deliver by 40 weeks even with unfavorable conditions

Mild Preeclampsia - Management • Management < 37 weeks remains controversial • Maternal and fetal evaluation? • Hospitalization vs ambulatory management? • Antihypertensive medications? • Bed rest?

Maternal Evaluation • Frequent evaluation for progression of disease • Lab evaluation • Platelet count • LFT's • Renal function • Urine protein • Repeat weekly – mild disease, no progression

Fetal Evaluation • Weekly antepartum fetal evaluation • Twice weekly testing with IUGR or oligohydramnios • Daily fetal movement assessment • Fetal growth evaluation

Outpatient Management • SBP ≤ 150mm / DBP ≤ 100mm • Urine protein ≤ 1000 mg/24 hours • Asymptomatic • Normal LFT's • Platelets ≥ 1000/mm3 • Daily BP and urinalysis • Twice weekly evaluation • Growth and fluid assessment q 3 weeks • Hospitalize with disease progression

Antihypertensive Medication • Mask diagnosis of severe disease • Lower rates of progression to severe disease • No demonstrated impact on perinatal outcome • No difference in GA at delivery* • Reduction in BP has not been associated with a reduction in antepartum days* *Sibai

et al AJOG 1992;167:879

Bed Rest • No evidence that bed rest improves outcome • No randomized trials • Increased risk of thromboembolism

Magnesium Sulfate Prophylaxis • > 70 years of use • Intramuscular (Pritchard) and intravenous (Sibai) regimes • "Standard of care" in the US • 10 % progression to severe disease with prophylaxis or placebo in 135 women at term* • 12.8 % vs 16.8 % progression in a recent controlled trial of MgSO4 vs placebo** *Witlin, Friedman, Sibai AJOG 1997;176:623-7 **Livingston et al Ob Gyn 2003;101:217-220

Severe Preeclampsia • SBP ≥ 160mm or DBP ≥ 110mm on 2 occasions 6 hours apart at bed rest • Significant proteinuria (≥ 5 g/24 – hr) • Oliguria < 500 mL / 24-h • Cerebral / visual disturbances • Epigastric pain, nausea, vomiting • Pulmonary edema, cyanosis • Abnormal LFT's • Thrombocytopenia • IUGR

Severe Preeclampsia • Hospitalization • MgSO4 prophylaxis • Antihypertensive medication • Maintain SBP 140 -155mm and DBP 90 -105mm • 24 - 34 weeks • Steroids for lung maturity • Maternal assessment • Fetal assessment

Antihypertensive Medication Hydralazine

Labetalol Nifedipine

5 mg IV or 10 mg IM. Repeat at 20 min intervals pending response. Repeat prn when controlled (usually 3 hrs). Max dose 20 mg IV or 30 mg IM. 20 mg IV bolus initially, then 40, 80, 80 mg every 10 minutes for max 220 mg. Caution with asthma, CHF. 10 mg po. Repeat in 30 min if necessary.

HTN unresponsive to other drugs or hypertensive encephalopathy. 0.25 Sodium Nitroprusside µg/kg/min to max 5 µg/kg/min. Fetal cyanide toxicity if used > 4 hrs. National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy. AJOG 2000;183:S1-S22.

Antihypertensive Therapy • Prevent potential cerebrovascular and cardiovascular complications • Encephalopathy, hemorrhage, CHF • No randomized trials to determine what level to treat to prevent complications • Recommendations vary • SBP ≥ 180mm and DBP ≥ 110mm • SBP ≥ 160 mm or DBP ≥ 105mm • MABP ≥130mm • Sibai Ob Gyn 2003;102:181 • Intrapartum – SBP ≥ 170mm or DBP ≥ 110mm • Postpartum or thrombocytopenia – SBP ≥ 160mm or DBP ≥ 105mm

Severe Preeclampsia • Progressive deterioration in both maternal and fetal conditions • Deliver with onset after 34 weeks • Increased rate of maternal morbidity/mortality • Significant fetal risk • Delivery prior to 34 weeks • Imminent eclampsia • Multiorgan dysfunction • Severe IUGR • Suspected abruption • Non-reassuring fetal testing

Severe Preeclampsia < 34 Weeks • Considerable disagreement • Delivery is definitive therapy • Delivery may not be optimal for the premature fetus • ≥ 34 weeks – deliver • < 23 weeks – offer termination • 33 - 34 weeks – steroids with delivery after 48-hrs • 23 - 32 weeks gestation • Individualized treatment based on clinical response during the initial 24 hours observation

Chronic Hypertension • 5 % of pregnant women • Hypertension before the 20th week or before pregnancy • Antihypertensive medication prior to pregnancy • Persistence beyond the usual postpartum period • Mild chronic hypertension • ≥ 140 / 90 mm Hg • Severe chronic hypertension • ≥ 180 / 110 mm Hg

Chronic Hypertension • Essential hypertension (90%) • Secondary hypertension (10%) • Renal • Connective tissue • Endocrine • Vascular

Chronic Hypertension • Risks • Superimposed preeclampsia • 4.7 – 52% incidence • Abruption • Poor perinatal outcome • IUGR • IUFD • PTD

Low Risk Chronic HTN • Mild essential hypertension without organ involvement • Blood pressure at initial visit regardless of medication • BP < 180 / 110 mmHg • No previous perinatal losses

Low Risk Chronic HTN • Usually good perinatal outcome irrespective of antihypertensive drugs • 49% ↓ MAP • 34% with no change in MAP • Most poor outcomes were related to superimposed preeclampsia • Discontinue antihypertensive meds • Treat BP > 160 / 110 mmHg to keep DBP ≤ 105 mmHg • In absence of superimposed preeclampsia, pregnancy may continue • Favorable cervix • Labor • Completion of 40 weeks

High Risk Chronic HTN • Secondary hypertension • Maternal age > 40 • Duration HTN > 15 years • Target organ damage • Previous perinatal loss • BP ≥ 180 / 110 mmHg

High Risk Chronic HTN • Antihypertensive medication • Absent target organ damage • Maintain BP 140 -150 / 90 -100 (140 -160 / 90 -105) • Target organ damage • BP < 140 / 90 • Close monitoring • Fetal evaluation at 28 (as early as 26) weeks • Superimposed preeclampsia • Hospitalization • Delivery with GA ≥ 34 weeks

Medication for BP ≥180/110 Drug

Starting dose

Max dose

Acute treatment Hydrazaline

5-10 mg IV q 20 min

30 mg

Labetalol

20-40 mg IV q 5-10 min 220 mg

Nifedipine

10-20 mg po q 30 min

50 mg

Methyldopa

250 mg bid

4 g/d

Labetalol

100 mg bid

2400 mg/d

Nifedipine

10 mg bid

120 mg/d

Thiazide diuretic

12.5 mg bid

50 mg/d

Long-term treatment

Superimposed Preeclampsia • Incidence 4.7 - 52% depending on initial BP • Exacerbation of HTN • At least ≥ 30 mm systolic or ≥ 15 mm diastolic • Development of proteinuria • ≥ 500mg / 24 h • Exacerbation of preexisting proteinuria • ≥ 5 g / 24 h • ↑ LFT's • ↓ platelets • ↑ uric acid > 6 mg / dL • Development of symptoms